1. Field
The described technology relates generally to a bonding apparatus and a method thereof for a display device.
2. Description of the Related Art
An organic light emitting diode (OLED) display includes a display substrate providing a pixel area and a non-pixel area, and an encapsulation substrate disposed to face the display substrate for encapsulation and combined to the display substrate by a sealant such as an epoxy. In the pixel area of the display substrate, a plurality of light emitting elements connected between scan lines and data lines in a matrix method thereby forming pixels are formed, and in the non-pixel area, the scan lines and the data lines of the pixel area are extended and a scan driver and a data driver processing signals provided from the outside through a pad are formed to supply the signals to the scan lines and the data lines. The scan driver and the data driver including a driving circuit processing the signals provided from the outside to generate a scan signal and a data signal may be formed in a manufacturing process of the light emitting element, or may be manufactured of a separated integrated circuit chip and may be mounted to the display substrate.
When an integrated circuit chip is manufactured and mounted to the display substrate, the integrated circuit chip may be mounted by tape automated bonding (TAB) in which the driving chip is mounted to a tape carrier package (TCP) and is connected to the pad of the display substrate, or as a chip on glass (COG) method in which the driving chip is directly attached to the pad of the display substrate. Among them, the chip on glass (COG) method has a simple structure and occupies a small area compared with the tape automated bonding method such that the chip on glass (COG) method is widely applied to a small and medium display panel of a mobile communication product.
The chip on glass (COG) method is a method in which a bump formed at an input terminal and an output terminal of the driving chip is attached to an inner lead bonding (ILB) pad and an out lead bonding (OLB) pad formed in the display substrate through a conductive ball included in an anisotropic conductive film (ACF), and a flexible printed circuit (FPC) is connected to the input pad connected to the inner lead bonding pad by a film on glass (FOG) method. Accordingly, if the control signal and the data signal are provided through a flexible printed circuit (FPC) from the outside, the driving chip generates the scan signal and the data signal, and the generated signals are transmitted to the light emitting element through the scan line and the data line connected to the out lead bonding pad.
Particularly, in the chip on glass (COG) method, the driving chip is aligned to the display substrate attached with the anisotropic conductive film (ACF), and a load is applied by using a pressure tip of a bonding apparatus for the display device to connect the bump of the driving chip to the pad of the display substrate. However, when the thickness of the display substrate is decreased and the display substrate is made of a flexible material, the display substrate is bent such that it is difficult to obtain stable pressure quality by a bonding apparatus of the conventional display device.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.